Abstract Significant efforts have been devoted to develop efficient visible-light-driven photocatalysts for the conversion of CO 2 to chemical fuels. The photocatalytic efficiency for this ...transformation largely depends on CO 2 adsorption and diffusion. However, the CO 2 adsorption on the surface of photocatalysts is generally low due to their low specific surface area and the lack of matched pores. Here we report a well-defined porous hypercrosslinked polymer-TiO 2 -graphene composite structure with relatively high surface area i.e., 988 m 2 g −1 and CO 2 uptake capacity i.e., 12.87 wt%. This composite shows high photocatalytic performance especially for CH 4 production, i.e., 27.62 μmol g −1 h −1 , under mild reaction conditions without the use of sacrificial reagents or precious metal co-catalysts. The enhanced CO 2 reactivity can be ascribed to their improved CO 2 adsorption and diffusion, visible-light absorption, and photo-generated charge separation efficiency. This strategy provides new insights into the combination of microporous organic polymers with photocatalysts for solar-to-fuel conversion.
Photocatalytic CO
2
reduction into renewable hydrocarbon solar fuels is considered as a promising strategy to simultaneously address the global energy and environmental issues. In this study, a ...binary g-C
3
N
4
/ZnO photocatalytic system was constructed
via
a one-step facile calcination method and further used as a photocatalyst for CO
2
reduction. It was shown that the as-prepared g-C
3
N
4
/ZnO photocatalytic system exhibited enhanced photocatalytic activity for CO
2
reduction by a factor of 2.3 compared with pure g-C
3
N
4
, while maintaining the original selectivity of pure g-C
3
N
4
to convert CO
2
directly into CH
3
OH. For the first time, the coupling effect of ZnO responsible for the improved photoactivity of g-C
3
N
4
was fully illustrated and a direct Z-scheme mechanism rather than the conventional heterojunction-type mechanism was proposed to explain the better performances of the g-C
3
N
4
/ZnO binary composite photocatalytic system. The enhancement of photocatalytic CO
2
reduction activity is attributed to the highly efficient ZnO-to-g-C
3
N
4
electron transfer occurring at the intimate contact interface between the g-C
3
N
4
phase and ZnO phase. This work will provide new deep insights into the rational construction of a g-C
3
N
4
-based photocatalytic system and the design of a direct Z-scheme system without an electron mediator for photocatalytic CO
2
reduction reactions.
A direct Z-scheme g-C
3
N
4
/ZnO binary composite photocatalytic system was constructed and exhibited enhanced photocatalytic CO
2
reduction activity compared to g-C
3
N
4
or ZnO.
Porous graphitic carbon nitride (g-C
3
N
4
) was prepared by a simple pyrolysis of urea, and then a g-C
3
N
4
-Pt-TiO
2
nanocomposite was fabricated
via
a facile chemical adsorption followed by a ...calcination process. The obtained products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance absorption spectra, and electron microscopy. It is found that the visible-light-induced photocatalytic hydrogen evolution rate can be remarkably enhanced by coupling TiO
2
with the above g-C
3
N
4
, and the g-C
3
N
4
-Pt-TiO
2
composite with a mass ratio of 70 : 30 has the maximum photoactivity and excellent photostability for hydrogen production under visible-light irradiation, and the stable photocurrent of g-C
3
N
4
-TiO
2
is about 1.5 times higher than that of the bare g-C
3
N
4
. The above experimental results show that the photogenerated electrons of g-C
3
N
4
can directionally migrate to Pt-TiO
2
due to the close interfacial connections and the synergistic effect existing between Pt-TiO
2
and g-C
3
N
4
where photogenerated electrons and holes are efficiently separated in space, which is beneficial for retarding the charge recombination and improving the photoactivity.
A visible-light-responsive g-C
3
N
4
-Pt-TiO
2
nanocomposite with efficient photogenerated carrier separation in space was fabricated.
As a green energy carrier, a potential fuel and an essential chemical for the manufacturing of fertilizers, plastics, and explosives, ammonia (NH3) is currently produced by Haber−Bosch process. ...However, the process converting nitrogen (N2) into NH3 under strict conditions consumes substantial energy and releases enormous greenhouse gases. In the context of the global energy crisis and increasing greenhouse effect, it is urgent to explore mild, green, sustainable, and economic nitrogen‐fixation strategies. Very recently, photocatalytic nitrogen‐fixation reactions, including nitrogen reduction reaction (NRR) and nitrogen oxidation reaction (NOR), have aroused widespread attention due to its environmental friendliness and cost‐effectiveness. To achieve high photocatalytic performance and selectivity, it is necessary to design photocatalyst and its photoreaction system reasonably to optimize the light absorption, charge separation, mass transport, adsorption, and activation of N2 as well as proton/electron transfer. This review gives an overview of fundamentals, performance evaluation, and recent progress of the photocatalytic nitrogen‐fixation reactions. The photocatalysts and their design strategies are classified, and several suggestions are given for the analysis of the existing photocatalytic nitrogen‐fixation systems. Finally, a short perspective on the existing challenges and future opportunities are outlined for providing insights into the development of high‐efficiency photocatalytic systems for artificial N2 fixation.
Photocatalytic nitrogen‐fixation reactions including nitrogen reduction reaction (NRR) and nitrogen oxidation reaction (NOR) have aroused widespread attention. Herein, an overview of fundamentals, performance evaluation, and recent progress of the photocatalytic nitrogen‐fixation reactions is summarized. In addition, a short perspective on the existing challenges and future opportunities for photocatalytic N2 fixation are outlined.
Ag/AgX/BiOX (X = Cl, Br) three-component visible-light-driven (VLD) photocatalysts were synthesized by a low-temperature chemical bath method and characterized by X-ray diffraction patterns, X-ray ...photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and UV–vis diffuse reflectance spectra. The Ag/AgX/BiOX composites showed enhanced VLD photocatalytic activity for the degradation of rhodamine B, which was much higher than Ag/AgX and BiOX. The photocatalytic mechanisms were analyzed by active species trapping and superoxide radical quantification experiments. It revealed that metallic Ag played a different role for Ag/AgX/BiOX VLD photocatalysts, surface plasmon resonance for Ag/AgCl/BiOCl, and the Z-scheme bridge for Ag/AgBr/BiOBr.
A series of graphene oxide (GO)–cadmium sulfide (CdS) nanocomposites were fabricated via a facile precipitation process by using Cd(Ac)2, Na2S, and prefabricated GO as raw materials. The obtained ...GO–CdS nanocomposites are composed of CdS nanoparticles with an average diameter of ca.10 nm, which are well dispersed and immobilized on GO sheets. By using Na2S/Na2SO3 as sacrificial reagent, the GO–CdS nanocomposites exhibit higher photoactivity for hydrogen production than the bare CdS under visible-light irradiation. Among various composite photocatalysts prepared, 5 wt % GO–CdS shows maximum hydrogen production efficiency. Our findings demonstrate that the coupled GO can serve as CdS supporting matrix, cocatalyst, and electron acceptor for effective charge separation, and therefore provide an inexpensive means to achieve high-performance visible-light-driven photocatalysts for hydrogen production without noble metal-loading.
This perspective gives an overview of recent developments in heterogeneous photocatalytic CO
2
reduction for C1/C2 fuels production over semiconductors, which has been known for several decades as a ...potential feasible means to store intermittent solar energy and to recycle CO
2
. In recent years, significant efforts have been made in order to further improve the photoactivity and the selectivity through developing novel photocatalysts and its CO
2
photoreduction reaction systems, which would be of great interest in the field of solar conversion and CO
2
resource utilization.
This perspective reviews the recent developments in photocatalytic CO
2
reduction over semiconductors for CO
2
resource utilization.
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•Layered WS2/WO3 heterostructure is fabricated via in situ sulfurization of hydrous WO3.•2H-WS2 in the heterostructure possesses few-layer structure with a thickness of ...~4.2 nm.•Photoinduced charge transfer between 2H-WS2 and m-WO3 follows a Z-scheme mechanism.•Interfacial charge transfer is promoted by the intimate contact between 2H-WS2 and m-WO3.•WS2/WO3 heterostructure exhibits superior H2 generation activity over the pure 2H-WS2.
Solar-driven H2 production over Z-scheme photocatalysts to mimic the natural photosynthesis represents a promising approach to the production of clean hydrogen energy. However, fabrication of Z-scheme heterostructures with intimate interfacial contact and smooth charge transfer for efficient H2 generation is still challenging. Herein, a series of layered WS2/WO3 heterostructures containing monoclinic WO3 (m-WO3) nanoplates and few-layer hexagonal WS2 with 2H structure (2H-WS2) is constructed via an in situ sulfurization process of hydrous WO3 nanoplates. The electronic interaction between the two moieties (2H-WS2 and m-WO3) follows a direct Z-scheme mechanism to retard the charge recombination without weakening the redox ability of the photoexcited charge carriers of the WS2/WO3 heterostructures. Moreover, the few-layer 2H-WS2 with thickness of ~4.2 nm and intimate interfacial contact between 2H-WS2 and m-WO3 due to the “S-W-O” transition layer can further provide shortened charge migration path and smooth interfacial charge transfer, which in turn enables the effective operation of the Z-scheme mechanism. Therefore, the WS2/WO3 Z-scheme photocatalyst with an optimal component ratio delivers ca. 5 times higher H2 generation activity than the few-layer 2H-WS2 alone. The present work offers a promising strategy to construct integrated nanostructured heterostructures with intimate interfacial contact, smooth charge transfer and improved photocatalytic performance.
It is highly desirable to simulate natural photosynthesis by using sunlight to drive the overall water splitting without using external bias and sacrificial agent. Herein, few-layer monoclinic BiVO
4
...nanosheets (BVNS) with a thickness of (∼)4.3 nm, exposed (010) facets and abundant oxygen vacancies are fabricated using graphene oxide dots as templating reagent. After decorating with asymmetric chromium porphyrin derivative bearing one benzoic acid and three phenyls as meso-position substituents (chromium-5-(4-carboxyphenyl)-10,15,20-triphenylporphrin, CrmTPP) and PtO
x
cocatalyst, the obtained two-dimensional (2D) hybrid nanocomposite (BVNS/CrmTPP/Pt) with an optimal component ratio delivers a robust overall water splitting performance with a relatively high apparent quantum yield (8.67%) at 400 nm monochromatic light. The ultrathin structure and widely distributed oxygen vacancies on the exposed (010) facets of BVNS not only endow strong and intimate contact with the decorated CrmTPP molecules to promote a two-step excitation Z-scheme charge transfer mechanism for preserving the high redox ability of the photogenerated charge carriers, but also alleviate their recombination, and thus causing the robust overall water splitting performance of the 2D hybrid nanocomposites. The present results provide a novel strategy to construct highly efficient artificial photosynthetic system for overall water splitting.
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